1k Yard .300 win mag bullet

[Jimro]

Old Roper is correct, Berger doesn't make a 220.20x bullet, the one listed in the JBM bullet data repository that I used for calculations is evidently a typo. Someone must have fat fingered the input, and I didn't catch it, I was just looking for a good "heavy" bullet without going to the 230gr option.

Jimro

[emcon5]

Originally Posted by Mississippi

I know this. The hope with the higher BC is that if I do my part, the rig and projectile will do their part. I'm not High Master yet, but I have shot high master scores at 600 yards. My ability to call wind is improving, but I still make mistakes.

Hell, even High Masters get the wind wrong.

Originally Posted by Jimro

Well, that is certainly a technique,although I'd bet you'd choose differently if the .7 bullet were shooting 2.5 minute groups versus 0.5 minute groups with the .5 bc bullet.

Yeah, that is why I prefaced it with:

Originally Posted by me

provided the accuracy is acceptable.

Using the wind example I provided, I would certainly give up 1/4 MOA of accuracy to gain ~2 MOA less wind at 1K. If the delta was different, either worse in accuracy or closer in wind, I might go the other way.

Like you said, everything is a compromise.

[Stats Shooter]

I made a spreadsheet over the last couple days of every single match bullet For Sierra, Hornady, Berger, Lapua, nosler, and Barnes in .308 and .224. the list includes every weight, G1&g7 BC, bullet length and the length of the polymer tip where applicable. I had to call Hornady for the ELD lengths and Nosler for some of theirs...But this sure makes it nice for determining what will fit in a magazine and looking at BC vs weight.

One thing I noticed from the list is that quite often, a heavier bullet may have a lower G1 and G7 than a lighter bullet if similar design. The 175 vs the 180 Grain .308 Sierra match kings...The 175 has a higher BC than the 180's. Which begs the question: Why in the world would you shoot a potentially slower bullet with lower BC?
If it's a round nose hunting bullet that's one thing, but for wringing steel or punching paper why would anyone choose the 180 smk over the 175?

[Jimro]

Why in the world would you shoot a potentially slower bullet with lower BC?
If it's a round nose hunting bullet that's one thing, but for wringing steel or punching paper why would anyone choose the 180 smk over the 175?

Simply put, for unknown and mysterious reasons some rifles will shoot those slower bullets with less BC better than lighter bullets with higher BC. For known distance shooting this generally isn't a problem at all.

Historical example.... The 168gr SMK was designed for 300m shooting for the Olympics, and High Power shooters found that it worked very well out to 600 yards for across the course matches. The 173gr M72 match FMJBT ball round has always had the higher BC, but a lot of shooters using Garands would load up match ammo with the 180gr SMK (this was back before the boat tail geometry change).

Jimro

[Stats Shooter]

Simply put, for unknown and mysterious reasons some rifles will shoot those slower bullets with less BC better than lighter bullets with higher BC. For known distance shooting this generally isn't a problem at all.

Ahh, that makes sense. I know that most of the time a 1:10 twist is actually between 1:9.5 and 1:10.5 in most guns, even the same make and model will have slight variations in twist and/or chamber. So what works in one gun may not work in an identical one as well.

A high BC from a cartridge/gun combo producing 3 MOA groups doesn't do much good.